Clamp



Spt. 22, 1936'. A, R. DUVALL CLAMP Filed 0012. 3, 1933 Mfg.

- AT oRNY Patented Sept. 22, 1.936

CLAMP Allan R. Duvall, San Francisco, Calif., asslgnor, by mesne assignments, to Oliver United Filters Incorporated, San Francisco, Calif., a. corporation of Nevada Application October 3, 1933, Serial No. 691,975

3 Claims. (Cl. 21d-199) This invention relatesl to a clamp for securing or anchoring the edges of a sheet of material, such as cloth, paper, woven wire or sheet metal. More particularly the invention relates to a clamp 5 for securing the lter medium of a filter to its support, base or frame.

For the purpose of filtering sugar cane settlings resort has been made to a punched sheet metal filtering screen or medium, but considerable diilculty has been experienced in securing this type of filter medium to the cylindrical surface of a continuous sectionalized rotary drum lilter. As is well known in the ltration art, the drum of a continuous lter is divided into individual sections or compartments by spaced parallel division strips running longitudinally of the drum. To facilitate repair and inspection it isr oftentimes desirable to cover each section or compartment with an individual panel of iilter me- -720 dium, rather than to cover the drum with a single continuous sheet of iilter medium.. Oliver United.4 Filters Inc. with whom the applicant is associated has carriedon considerable development work for the purpose of developing 25 some means by which a perforated sheet metal filtering medium may be secured to the lter drum in the form of individual panels. One method which at first looked very promising was to form a dovetailed channel in each division 30 strip. The edges of two adjacent panels of the Y sheet metal ltering medium were then inserted into this channel and secured in place by means of a lead caulking strip. The caulking was effected under suiiicient pressure to force lead into 35 the perforations of the filtering medium. However, actual eld tests made by the applicant proved that within a period of two hours the ltering medium so secured had worked suiiiciently loose to prohibit the further operation of 40 the lter.

In general the object of this invention is the provision of a clamping mechanism by which the edge of a sheet of material can be securely but detachably anchored o r locked in place.

45 More speciiically the object of my invention is the provision of a base member having a channel therein formed with undercut walls, and within which a plurality of pairs of wedge shaped members is adapted to be accommodated for the pur- 50 pose of detachably locking a sheet of material between the adjacent faces of the wedges and e channel.

The invention possesses other advantageous features, some of which with the foregoing will 55 be set forth at length in the following description, where I shall outline in full that form of my invention which I have selected for illustration in the drawing accompanying and forming part of the present specication. In said drawing, I have shown one form of my inveni5 tion, but it is to be understood that I do not limit myself to such form, since the invention as set forth in the claims may be embodied in a plurality of forms.

Referring to the drawing: .l0

Figure 41 is a cross section of a portion of the periphery of a rotary drum filter illustrating one form of my invention as applied to the division strips of the filter.

Figure 2 is a'plain view of that portion of the l5 rotary drum filter shown in Figure 1 with a part oi the ltering medium broken away to show one of the filter compartments.

Figure 3 is a perspective view of one pair o coacting wedge shaped members utilized in my invention.

Figure 4 is a perspective view of a curved clamp adapted to be disposed peripherally of a lter drumwhen it is desired to divide the drum longitudinally into two individual iilters.

As shown in Figure 1 a division strip l is secured to a cylindrical shell 2 in any suitable manner, such as by riveting. Secured either directly to the shell 2 or in the event that shallow compartments are desired, toa spacing member 3, is a supporting screen provided with ribs 5 which serve to hold the iilter medium E in spaced relation with respect to the supporting screen 4i, to thereby form the lter section or compartment 1. As is well known in the industrycommunication is established between each of the lter compartments and the ltrate valve by means of suitable filtrate pipes 8 secured to the filter drum by means of a tting 9. The division strip I is provided with lateral flanges Il which overhang and rest on the edges of the supporting screen 4.

The division strip l is also provided with a channel l2 extending over its entire length, and it is to be particularly noted that the lateral walls of this channel are undercut, and of uniform cross section throughout its length. As is shown in Figure 1 the cross section of the channel |2`` is in the form of an isosceles trapezoid, but may be of any other form such as half round or inverted T so long as undercut walls are provided. Accommodated within this channel and forming a clamp therewith is a plurality of pairs of coacting wedge shaped members I3 and I4. As shown in Figures 1 and 3 the outer side of the 55 wedges are not only undercut but are slightly uted to snugly accomodate the upper edges of the channel I2. The wedges I3 and I4 are complementary so that when their inner faces are in engagement their outer edges are always parallel regardless of the relative linear position of the wedges. It is also to be noted that the combined cross sectional area of the coacting wedges is uniformV throughout their overlapping sections regardless of their relative linear posimaximum width of an individual wedge member, and that consequently the individual wedge members may be readily dropped into the channel. This construction is of importance for since the ends of the channel are closed by the ends or heads of the filter drum it would be impossible to insert the wedges endwise in the channels. Preferably a number of pairs of wedges are used. The first pair of wedge members should be moved to one extreme end of the channel, and then each subsequent pair made to abut the preceding pair. It will be found that the last pair can be inserted into the remaining length of channel only if this remaining length is somewhat longer than the length of any single wedge member. The

reason for this is of course that a wedging ofl clamping action can be obtained only so long as it is possible to increase the combined cross sectional area. of the coacting pair of wedge members by movingA each member of the pair longitudinally relative to each other. The unoccupied portion of the channel remaining after 'the last pair of wedge members has been inserted isv then distributed throughout the entire length of the channel by moving each pair backward to a slight extent so as to leave each pair slightly spaced from its adjacent pairs. As a iinal step the wedge members making up each coacting complementary pair are forced toward each other in a longitudinal direction to expand their combined cross sectional area and thereby securely closed by making each pair abut the preceding pair to `thereby leave suiiicient free space by which one of the wedge members can be removed from the channel.

To obviate any possibility of the loosening of the wedge members due to a dierence in the coeiicient expansion of the materials from which the base member ordivision strip II, the wedge members and the intervening ltering medium are made, it is desirable that all of these elements should be made either from the same kind of material or from materials which have substantially the same coeilcient of expansion.

Actual eld tests have shown that the type of clampl above described effectively holds the filter medium in place and furthermore permits the filter medium to be readily detached at will, either for the purpose of replacing any given panel of filtering medium or inspecting any compartment Without disturbing the remaining panels or compartments other than the two immediately adjacent panels and compartments.

Although my invention has been illustrated with particular reference to a rotary drum lter it is obviously applicable to any type of filter and may be used wherever it is of advantage to detachably secure or lock a sheet of material to a base of supporting member.V For example, in the construction of buildings this type of clamp may be conveniently used for securing the sheathing material. to the interior or exterior building walls.' By manufacturing the sheathing in standard sizes and using a clamp of this nature it would be possible to save considerable time and labor in constructing buildings.

I claim:

1. A clamp for fastening a iltering medium to the cylindrical surface of a rotary drum filter comprising: a division strip having a longitudinally extending channel therein formed with undercut walls and of substantially uniform cross section throughout its length; and a plurality of pairs of complementary and coacting wedge members accommodated within said channel.

2. In a rotary drum lter of the character described, a division strip; an undercut channel in said division strip adapted to accommodate one end of a filter medium and a plurality of pairs of complementary and co-acting wedge members disposed within said channel for locking said filter medium therein.

3. In a rotary drum lter of the character described, a division strip; an undercut channel in said division strip both ends of which are closed and within which one end of a filter medium is adapted to be accommodated; and a plurality of pairs of complementary and co-acting wedge members disposed within said channelfor locking said lter medium therein.

ALLAN R. DUVALL. 

